Biomass production of natural courses in arid lands and their valorisation by the camels

M Chaibou, B Faye* and P Lapeyronie**

Faculté d’Agronomie, Université Abdou Moumouni de Niamey BP 10960 Niger
Tel: 20 3152 37; Fax: 20 31 59 4
malamchaibou@yahoo.fr
* CIRAD 30/A Campus international de Baillarguet 34398 Montpellier Cedex 5 France
faye@cirad.fr
** Ecole Nationale Supérieure Agronomique de Montpellier (France) 2, Place Viala, 34060 Montpellier cedex1 France
lapeyron@ensam.inra.fr

Abstract

The arid areas are characterized by an annual rainfall less than 150 mm. Beside this very low quantity, rain is irregular over the space. In these conditions, the biomass production is very low in some places and absent in others. This study was carried in Agadez area (Niger), to assess the total fodder production of pasture as well as the quantity consumed by the camel.

The fodder production of the courses was studied by the method of " integral collect "of the grass contents in  the" small square" laid out through the surface sampling .The tree biomass production was estimated by using some "allometric regressions "established for some tropical trees.

The feeds intake was assess indirectly by chemical analysis of waste emitted by she- camels (n=8) eating on natural pastures. The ponderal performance growth was evaluated monthly by weighing the camel calves (n=7) with an electronic balance. The assessment of these fodder resources showed an annual production of 382 ± 82.92 kg DM.ha-1 which represented globally 213.08 ± 36.26 UFL.ha-1 and 11.17 ± 1.50 kg of DCP.ha^-1. The ingestion of the dry matter (DM) on pasture varies from 1.20 to 2.19 kg of DM100 kgof body weight with an average of 1.63 ± 0.28 kg of DM by 100 kg of body weight. Despite the low production of fodder, the camels recorded a very appreciable daily body profit varying from 277 g to 374 g. 

Key words: Biomass production, camel, feed intake, growth, Niger

Introduction

In Africa, the arid regions represent 54.6 p.100 of all the lands (Baumer 1995). These lands are considered, in the majority of the cases, like unproductive and not exploitable. In Niger, (sahelian country) the arid lands take about 77p.100 of total surface of the country. In these arid areas considered as uncultivated, breeding was practiced since immemorial time, in particular the  camels  breeding, animal adapted well for these spaces without many resources. This study carried out in the pastoral area of Agadez aims to assess the feeds resources production in this medium, as well as zootechnical results of the valorization of these resources.

Materials and Methods

Presentation of area study

The area of Agadez is located approximately at 950 km in the North-East of Niamey. It is an arid zone in reference to the  definition of Monod and Durou (1988), which stipulates that an arid zone is one  where the annual precipitations obtained, are always lower than 150 mm, and characterized by a very rarely and no vegetation and very poor grounds. The average of the precipitations recorded at the weather station of Agadez from 1993 to 2002 is of 134 mm. Agadez position in 1990 was under the isohyet 150 mm (Breman and De Ridder 1991). The pastoral periurban area of Agadez is usually habited  by Touaregs breeders who have composite herds  dominated by camels . The management style of these breedings is built primarily on mobility with circular and iterative movements in several directions.

Methods study of available biomass fodder

For the ligneous tree the foliar biomass was only quantified, which, represents particulary in this zone the essential of fodder consumed by animals in dry season. This assessment was made at the beginning of the dry season (October). In order to evaluate the biomass production on these vegetations used by camels, it was used allometric equations, which make it possible the calculation of the "maximal productivity foliar biomass" using some physical parameters of trees. The method was consisted, to lay down a placette of 100 m x 100 m (1 ha) through the site of study. Inside each placette, and on each tree, we measure some physical parameters of trees like circumference of the trunk trees to 20 cm of the ground (C), the height of the tree (H), the covering on the ground of the houpper (by measuring the two diameters (small= D1 and big=D2), the height from the ground to the lowest branch (HBB),…

In the Sahel some trees were studied by  authors like Cissé (1980), Poupon (1980), Piot et al (1980).They have finally  established some significant linear regressions between the foliar biomass (B) of a tree and some its physical parameters.

For herbaceous biomass the evaluation was carried out at the end of the growing period of vegetation in other words at epiaison stage (September-October) to quantify stock of fodder available for the dry season. The method used (Grouzis and Sicot 1980) was the" integral harvest" in small placette of 1m x 1 m on many sites of each type of course. Those  placettes were laid down  systematically along two (2) perpendicular axes in order to interest the whole of the selected site (according to the homogeneity of the vegetation and the desired precision).

Assessment of feeds intake

The indirect method by collecting fecal matter was used. The collections of fecal matter were carried out on eight (8) she-camel belong to 4 herds from different zones (1, 2 and 3).

To collect fecal matter emitted by  she-camels, they were followed since departure of the park the morning until they came back in the evening and all deposit were manually collected during the day. The analysis of the samples obtained made it possible, not only to have an idea on the digestibility but also indirectly the evolution of the quantity of feeds really intake per day. Knowing the quantity of excreted dry matter, the digestibility of the dry matter, the quantity of dry matter intake can be known by using the following equation.

DMI: dry matter intake (kg); DM(F): fecal dry matter; dDM: digestibility of dry matter in p. 100.

Nutritive value of intake fodder

The digestibility of the organic matter (OMD) and the content of digestible crude protein (DCP) of intake feeds were estimated from the chemical composition of deposit (fecal matter). The quantities of OM consumed during the day of grazing (voluntary intake organic matter; MOvi) were estimated according to the total fecal excretion (excreted fecal matter, OMf) per day of she-camels. The equations of forecast of the feeds nutritive value of the rations by using chemical composition of deposit, made it possible to quantify the energy and digestible crude protein (DCP) brought to the animal body during the day of pasture (Guerin et al 1989).

                                                                                                                          R²                 

            OMD = 0.0728 CP ²(f) -3.0 CPadf (f)-0.31 OM(f) + 80.50              0.91         

            DCP = 1.30 (CP- CPadf (f)) + 0.53 CF (f) – 25.2                           0.86   

OMD: digestibility of organic matter; CP: crude protein; CPadf: crude protein in ADF

OM: organic matter;    DCP: digestibility of crude protein;   CF: crude fiber;

ADF: acid detergent fiber

With: OMD in  p.100 of OM; OM in p.100 of DM ; other parameters : exprimed in p.100 of OM.

Ponderal growth camel calves

The ponderal growth of animals, was used to appreciate the zootechnical result of the relations plant-animal. Which ponderal growth allow the rations intake by the dromedary on natural courses? For camel calves, the evolution of their growth according to the food system was measured by a follow-up of the weight and the daily average profit weight (GMQ), by regular weighing using an electronic balance.

Results

Productivity of natural courses

In order to assess the production average of the dairy area,  it was summarized, on table 2, the production of each zone. According to our observations made on the ecology and the physical characteristics of zone 1 and 2, on their production in herbaceous biomass (zone 1: 410 kgDM.ha^-1 and zone 2: 454 kg of DM.ha^-1), and on their density in trees and shrubs (23 trees per hectare for zone 1 and 22 trees in a hectare for zone 2), it was considered that their difference, by test of comparison, is not significant (P<0.05). So we considered a same productivity for the zone 1 and 2, which made it possible to calculate the average production of the dairy area. Concerning the CP and DCP,  herbaceous's production is very weak and was considered negligible compared to the ligneous biomass production.

Feed intake of dromedary camel

The results obtained showed that the dry matter intake varies from 1.20 to 2.20 kg of DM per 100 kg of body weight. However the average was 1.63 ± 0.28 kg per 100 kg . Indeed, the average of weight of our camels does not exceed 350 kg. The maximal ingestion was observed in March with 3834 kg of DM intake and the minimal ingestion (2.10 kg of DM) in July. As for OM, it follows the same variation during time than DM intake. The average quantity of intake OM was 1.8 ± 0.15 kg of OM per animal so 0.50 ± 0.0377 kg of OM by 100 kg of body weight. The evolution of the ingestion of the dry matter and the organic matter (Figure 1).

Figure 1: Evolution of the intake feeds on natural courses by she-camels

It is appeared judicious to know the relation which exist between the intake dry matter, the digestibility of the organic matter and the quantity of excreted fecal matter. With data collected it was modelize this relation by a simple regression like Z = aX + By+ c  integrating the various parameters whose logarithmic transformation gives the following equation:

      Ln (DMI) = 0.58*Ln (Qf) – 2.20*Ln (OMD) – 1.25      R² = 0.74

DM: dry matter (kg); OMD: digestibility of organic matter in p.100 of OM ; Qf: quantity of fecal matter( kg) ; Ln: neperian logarithm

Ponderal performance of camel calves

Seven (7) camels calves whose two (2) male and five (5) female, was the subject of follow-up during 13 month.  The principal indicator of the performance measured on animals is the profit of daily average weight (GMQ). The average of this GMQ varied from 277 to 321 g of body weight per day for camel calve whose mother was milked and 374 g of live weight per day for the camel calve  whose mother was not milked. The best GMQ is recorded on camel calve male (321g per day) in zone 1. The weakest GMQ is recorded in zone 2 on a camel calve female with 277 g per day.  The GMQ obtained over all the period of follow-up are presented in table 3.

Discussion

Production of natural courses

The total production of biomass is low (382 kg of DM.ha ^-1). In 1981 Klein et al. found in a northern sahelian zone (Ekrafane) in Niger, similar with our zone, a maximum herbaceous production of 680 kg DM.ha^-1 without counting the woody production. Peyre de Fabrègues (1972) also finds in the zone of Tamesna located at the south-west of Agadez, a herbaceous production going from 0.50 to 1 tonne of DM.ha^-1.  It is noted that zone 1 (Ikirkiwi) offers an abundant ligneous foliar biomass (30.62 kg of DM.ha^-1). It also provides an important quantity of crude protein become from ligneous (12.24 kg DCP.ha^-1).  The zone 3 is the least productive about ligneous and herbaceous biomass (respectively  24.73 and 240 kg.ha^-1). Its woody fodder offers less energy and DCP  than the two other zones. Concerning DCP, the herbaceous's production of MAD is very weak and was considered negligible compared to that of the ligneous biomass.

Feed intake

The average of dry matter intake was 1.63 ± 0.28 kg per 100 kg of weight body. This value corresponds to an average ingestion of 2.85 kg of DM per animal during 24 hours. These results are in adequacy with those found by Kamoun et al (1989) wich was 1.40 to 1.80 kg DM by 100 kg of body weights obtained with she -camel feeds with the corn straw.

Ponderal performance growth of camel calves

In zone 1 which is very near of Agadez (9 km), the fluctuation is more important with four (4) periods of profit of average weight.  In fact zone 1 (tables 2), has the best availability of natural feeds resources. Moreover, the proximity of the campings with the urban centre (8 to 15 km), favour the access to feeds complementation. These GMQ weak are compared with those found by some authors in particular Kamoun et al (1989), Richard (1989) and Field (1984). These authors respectively found 326 to 525 g/day according to the periods of trial in station, 350g of weight per day for camel calve male and 244 g of body weight per day for camel calve female, whereas the third author records 317g of weight per day in an extensive system. Our results approach more those of this last author, because of the type of the system of breeding. The difference in growth for animals of the same sex, coming from the same breeding farm can be related to a difference in performance of the mothers, to the health integrity of the animal or related to some intrinsic factors in this animal.

Conclusion

• This study showed that the total production of biomass in this area is very low (382 kg of DM.ha^-1). In 1981 Klein et al found in a northern sahelian zone (Ekrafane) a maximum herbaceous production of 680 kg DM.ha^-1 without counting the woody production. But despite this productivty very low, camels of this area used efficiently the available biomass which procur them a veritable profit of weight. The average of intake dry matter founded was 1.63 ± 0.28 kg of DM per 100 kg of body weight. The must important profit weight (GMQ) recorded was 321g per day. However these ponderal performances recorded in this dairy area of Agadez must be considered because of multiple problems met under these conditions of breeding (milked, parasitism, mobility, low food availability,.), whose ineluctably affect the growth of these animals.

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Received 8 August 2010; Accepted 19 April 2011; Published 3 August 2011

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